SEASONAL VARIATIONS OF NUTRIENTS AND CHLOROPHYLL A IN THE COASTAL WATERS OF THE EDREMIT BAY AND THE TROPHIC INDEX (TRIX) VALUES OF THE ENVIRONMENT

Abstract

This first comprehensive study was carried out on current ecological quality status of Edremit bay between the years of 2003 and 2004. The samples were seasonally collected from 5 different depths (0.5-20 m) at 3 stations determined from shore to offshore. During the study, temperature, salinity and dissolved oxygen levels of the seawater ranged between 13.0-26.5 degrees C, 35.9-38.8 ppt, and 2.69-11.2 mg L(-1), respectively. Nitrate+nitrite-N (0.05-2.63 mu g-at L(-1)), phosphate-P (0.19-0.66 mu g-at L(-1)) and silicate-Si (0.49-4.92 mu g-at L(-1)) concentrations were measured, and also chlorophyll a values ranged between 0.1-2.2 mu g L(-1). The lowest and highest level of N:P ratio were obtained to be 0.16 and 11.32, respectively, and also this ratio was recorded lower than Redfield ratio (16:1). This result indicates that the studied region is oligotrophic in nature. Trophic Index (TRIX) values, which were calculated in the study to describe water quality, were between 0.86 and 2.98, reflecting high quality of water (range of 0-4). According to the Trophic Index, this region has the lowest trophic level but the highest quality status.